The present invention relates to an acoustically responsive sensor switch that is particularly suited for use, as a throat pickup switch for example, by physically handicapped persons to permit such persons to operate devices that are adapted to be responsive to a single input signal.
With the increased development of devices which allow physically impaired persons to perform various tasks which previously required the assistance of an aide, the need has arisen for the development of a sensor switch which can be actuated by even the most severely handicapped individuals with a simple body function. Many devices which require normal motor capabilities to operate, can be adapted to function in response to a single input signal. Accordingly, it is the purpose of the present invention to provide a sensor switch that will permit a physically handicapped individual to operate such devices. A typical application of the present invention would be as a throat pickup switch that is actuable by a grunt or hum.
Basically, the present invention comprises a transducer that is adapted to produce an electrical signal in response to the detection of a localized acoustical sound, and a conditioning circuit that is adapted to convert the audio signal from the transducer into a single square-wave pulse. Since the audio signal produced by the transducer will typically comprise a damped sinusoidal waveform, it is desirable that the conditioning circuit convert the audio signal to a simple ON/OFF signal which is better suited for switching purposes. In the preferred embodiment, this is accomplished by providing the audio signal through a threshold comparator circuit to a "debounce" circuit which has a response time slower than the frequency of the audio signal. The output signal therefrom is then provided to a Schmitt trigger circuit having preselected turn-on and turn-off thresholds which cause the circuit to produce a single square-wave output signal that coincides approximately with the duration of the acoustic sound.
Additional objects and advantages of the present invention will become apparent from a reading of the detailed description of the preferred embodiment which makes reference to the following set of drawings in which :